U.S. patent number 4,072,154 [Application Number 05/691,032] was granted by the patent office on 1978-02-07 for sealing arrangement for heart pacer electrode leads.
This patent grant is currently assigned to Cardiac Pacemakers, Inc.. Invention is credited to Jon A. Anderson, Wendell R. Malin.
United States Patent |
4,072,154 |
Anderson , et al. |
February 7, 1978 |
Sealing arrangement for heart pacer electrode leads
Abstract
An improved electrode sealing arrangement for use on lead
assemblies to be coupled to an implantable pulse generator to form
a cardiac pacer apparatus. The conductive portion of the lead
includes a terminal pin which is both rigid and durable, and which
is arranged to be clamped between a set screw and a terminal post.
The improved sealing means includes a generally closed cylindrical
resilient segment which is arranged generally coaxially of the lead
conductor, with a resilient peripheral sleeve extending outwardly
of the cylindrical segment and having a raised resilient ring
extending continuously about the outer periphery of the peripheral
sleeve. The raised resilient ring is disposed axially outwardly
from the distal end of the terminal pin, so as to provide an axial
displacement between the terminal pin and the resilient sealing
ring. Since the peripheral seal arrangement permits substantial
canting and deflection of the lead assembly within the tubular bore
formed in the pulse generator without adversely affecting the
sealing conditions, ease of lead insertion is facilitated due to
the increased tolerances which may be employed between the inner
end of the lead and the pulse generator connector block.
Inventors: |
Anderson; Jon A. (New Brighton,
MN), Malin; Wendell R. (Edina, MN) |
Assignee: |
Cardiac Pacemakers, Inc. (St.
Paul, MN)
|
Family
ID: |
24774902 |
Appl.
No.: |
05/691,032 |
Filed: |
May 28, 1976 |
Current U.S.
Class: |
607/37;
174/152GM; 277/626; 439/271 |
Current CPC
Class: |
A61N
1/3752 (20130101); H01R 13/5224 (20130101); H01R
13/20 (20130101); H01R 24/76 (20130101); H01R
2101/00 (20130101) |
Current International
Class: |
A61N
1/372 (20060101); A61N 1/375 (20060101); H01R
13/52 (20060101); H01R 13/02 (20060101); H01R
13/20 (20060101); A61N 001/36 () |
Field of
Search: |
;128/418,419P,419PG,421,422,423 ;339/6R,6C,94R,94C
;277/183A,177 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Kamm; William E.
Attorney, Agent or Firm: Haugen; Orrin M. Nikolai; Thomas
J.
Claims
We claim:
1. In combination, a lead assembly and an implantable pulse
generator forming a cardiac pacer apparatus:
a. said lead assembly comprising an elongated generally tubular
lead having a conductive element disposed therewithin, with
electrode means coupled to said conductive element and disposed at
the distal end of said lead assembly, and electrical and mechanical
connector means at the proximate end thereof for coupling said lead
assembly to said pulse generator;
b. said pulse generator comprising an enclosure having a bore
formed therewithin for receiving said connector means in sealed
relationship within said bore, connector block means disposed
within said bore for securing the proximal end of said conductive
element to said pulse generator and sealing means disposed about
the periphery of said lead assembly at a point adjacent said
proximal end and normally disposed within said bore when said lead
is coupled to said connector means;
c. said sealing means including a generally closed cylindrical
resilient segment arranged generally coaxially of said conductive
element with a resilient peripheral sleeve extending outwardly of
said cylindrical segment and with a first raised resilient ring
disposed about the periphery of said cylindrical segment and
disposed between the base of said cylindrical segment at the
proximal end thereof and the proximal end of said peripheral sleeve
and with a second raised resilient ring extending continuously
about the outer periphery of said peripheral sleeve, said resilient
peripheral sleeve having axially extending portions arranged in
oppositely disposed relationship of said second raised resilient
ring; and
d. a rigid terminal pin member disposed generally coaxially
thereof, with one end of said pin being lockingly received within a
bore formed in said connector block means and with the other end of
said rigid terminal pin being spaced axially inwardly of said
resilient peripheral sleeve and outwardly of said first raised
resilient ring.
Description
BACKGROUND OF THE INVENTION
The present invention relates generally to an improved lead
assembly for use in combination with an implantable pulse generator
to form a cardiac pacer apparatus, and more specifically to a
system for sealing the lead assemblies into place in the
implantable pulse generator so as to accommodate ease of assembly
during implant and to resist during the extended implant period,
any influx of body fluids which could interfere with normal
operation of the pulse generator, and thereby detract from the
efficiency of the pacer apparatus.
Cardiac pacers are employed at the present time to treat various
problems in the heart, including treatment of arrhythmias or other
disorders which require external stimulation to sustain adequate
cardiac output. Cardiac pacers in use today include asynchronous
units as well as demand-inhibit units, with the selection being
indicated by the patient's condition.
Artificial electronic pacers very nearly approximate the electrical
impulses normally delivered by the natural cardiac conduction
network. These electronic pacers consist of a pulse generator and
an insulated conductive wire lead, the pacer emitting small,
sequentially timed electrical impulses which cause the ventricular
heart muscles to contract. In a normal person, ventricular
contractions result from depolarization caused by transmission of
signals from the sino-atrial node through the atrial-ventricular
node and the Common Bundle (His) to the right and left bundle
branches and the Purkinje Network. When a segment of this natural
conduction system becomes blocked, such as when there is no
conduction through the Bundle of His, an artificial pacer is
normally required to maintain an adequate and appropriate heart
rate and rhythm.
In an implantable cardiac pacer assembly or system, the combination
of a pulse generator and lead is employed, the term "pulse
generator" normally refers to the implantable electronic device,
while the term "lead" refers to the insulated conductive wire which
is electrically and mechanically coupled to the pulse generator and
which receives the stimulating impulse from the pulse generator and
transmits this impulse to the heart. The lead incorporates an
electrode which is the conductive element or contact, normally
exposed, on or adjacent the distal end of the lead to establish
electrical contact with the heart muscle.
In an implantable system, either endocardial leads or myocardial
leads may be employed. Endocardial leads are those leads which
enter the heart through a vein and make contact with the
endocardium, while myocardial leads are those which are attached to
the surface of the heart with an electrode making contact with the
myocardium.
Established procedures are employed for the lead placement, with
these procedures being well known in the art. Following placement
of the lead, electrode thresholds are determined and upon an
indication of satisfactory thresholds, the proximal ends of the
leads are connected to the pulse generator. This connection is
normally accomplished by the insertion of the exposed terminal pin
of the lead into the connector block of the pulse generator.
Inasmuch as the terminal pin and the connector block have exposed
conductive surfaces, it is essential that the zone surrounding the
terminal pin-connector block assembly be sealed and maintained free
of body fluids. Leakage of body fluids into the cavity or zone
occupied by the terminal pin-connector block combination may
adversely affect pacer performance, hence durable seals must be
provided.
The procedure for inserting the leads into the pulse generator must
be one which can be accomplished with a maximum degree of freedom,
so as to avoid inadvertent moving of the placed electrode and lead.
This requires, in turn, that the insertion of the terminal pin into
the connector block be accomplished with ease. Regrettably, as one
attempts to facilitate ease of insertion of the terminal pin into
the connector block, one further complicates or interferes with
normal sealing between the proximal end of the lead and the pulse
generator. In accordance with the present invention, however, an
improved sealing arrangement is provided which enables ease of
insertion of the terminal pin into the connector block, without
adversely affecting the quality of the seal.
In order to improve the quality of the seal and for mechanical
integrity, the terminal pin extends axially into that portion of
the lead which is received within the body of the pulse generator.
The terminal pin, which is durable and rigid, preferrably
terminates at a point axially spaced inwardly from the zone of the
seal. Therefore, the rigid pin may be accommodated within a bore
formed in the connector block, with the bore formed in the
connector block being of a radial dimension sufficiently great so
as to readily receive and accommodate the exposed portion or
segment of the terminal pin. Thereafter, when the set screw is
forced against the surface of the exposed portion of the terminal
pin, any radial deflection of the terminal pin may be accommodated
without adversely affecting or destroying the seal established
between the lead and the lead accommodating bore formed in the
pulse generator.
SUMMARY OF THE INVENTION
Briefly, in accordance with the present invention, the proximal end
of the lead is provided with a generally closed cylindrical
resilient segment which terminates adjacent the exposed terminal
pin, with the cylindrical resilient segment being further provided
with a resilient peripheral sleeve extending outwardly of the
cylindrical segment and with a raised resilient ring extending
continuously about the outer periphery of the peripheral sleeve.
This sealing arrangement is preferably disposed at a point remote
from the terminal pin in order to provide a flexible transition
which is as smooth as possible under the circumstances. The
flexible transition is further accommodated by disposing or placing
the inner end of the terminal pin at a point spaced from the outer
peripheral seal. The flexible transition must have a finite
dimension in order to improve the operational features of the
structure. The physical configuration of the seal permits,
therefore, both deflection and canting of the cylindrical segment
of the lead containing the rigid terminal pin without adversely
affecting the sealing characteristics of the seal system.
Therefore, it is a primary object of the present invention to
provide an improved seal arrangement for a lead assembly used in
combination with an implantable pulse generator to form a cardiac
pacer system.
It is a further object of the present invention to provide an
improved seal arrangement for a lead assembly utilized in
combination with an implantable pulse generator of a cardiac pacer
system, and wherein the seal arrangement effectively isolates the
mated connector block-terminal pin combination, while facilitating
ease of assembly of the terminal pin within the connector block
arrangement.
It is yet a further object of the present invention to provide an
improved sealing arrangement for a lead assembly used in
combination with an implantable pulse generator forming a cardiac
pacer system, and wherein modest misalignments between the lead
assembly and the lead assembly receiver of the pulse generator may
be accommodated without adversely affecting the sealing surface
therebetween.
Other and further objects of the present invention will become
apparent to those skilled in the art upon a study of the following
specification, appended claims, and accompanying drawing.
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 is a perspective view of an implantable pulse generator
having a lead assembly coupled thereto, with a portion of the lead
assembly being broken away;
FIG. 2 is a side elevational view, partially in section, and
illustrating the pulse generator-lead assembly combination shown in
FIG. 1, with the lead assembly being fragmented in order to show
the electrode at the distal end thereof, and with the sectional
portion of FIG. 2 being taken along the line and in the direction
of the arrows 2--2 of FIG. 1;
FIG. 3 is a partial vertical sectional view on a slightly enlarged
scale, and illustrating the manner in which the lead assembly is
received within the bore formed in the pulse generator body, and
illustrating the plug seal component in exploded disposition
relative to the pulse generator; and
FIG. 4 is a view similar to FIG. 3, and illustrating the structure
with the terminal pin of the lead assembly firmly engaged by the
connector block of the pulse generator, and illustrating, in
slightly exaggerated form, the misalignment or canting which occurs
between the proximal end of the lead assembly and the lead assembly
receiver, and further illustrating the effective seal existing
between the periphery of the lead assembly and the bore of the
pulse generator.
DESCRIPTION OF THE PREFERRED EMBODIMENT
In accordance with the preferred embodiment of the present
invention, and with particular attention being directed to FIGS. 1
and 2 of the drawing, it will be seen that the cardiac pacer
apparatus or system generally designated 10 includes lead assembly
11 along with pulse generator 12. As is apparent from FIG. 2, the
lead assembly 11 consists of an elongated generally tubular
structure having a conductive element disposed therewithin, such as
is illustrated in the broken away zone at 14, and with an electrode
15 at the tip of the cone being coupled to the conductive element
and disposed at the distal end of the lead assembly. The lead
assembly 11 may be constructed in accordance with the lead assembly
disclosed in, the David Charles Amundson U.S. Pat. No. 4,033,355;
and assigned to the same assignee as the present invention.
As is apparent, a transparent epoxy member 17 is coupled to the
enclosure 18 of the pulse generator 12, with epoxy member 17 having
a bore 19 formed therewithin to receive the proximal end of lead
assembly 11. With attention being directed to FIG. 3 of the
drawing, the proximal end of lead assembly 11 includes a generally
closed cylindrical resilient segment 20 arranged generally
coaxially of conducting element 14, with the conductive element 14
terminating in terminal pin 22. Sealing means are provided about
the periphery of cylindrical segment 20, as at 23 and 24, with the
latter sealing means being described more fully hereinafter.
Pulse generator 12 is provided with an output lead member 26 which
is arranged to pass through a seal member, and ultimately make
contact with connector block generally designated 28. Connector
block 28 includes a base or anvil member 29 having an upper tapped
portion 30 with a set screw 31 threadably received therewithin. Set
screw 31 is arranged to be screwed inwardly in member 30 and
ultimately engage for mechanical and electrical purposes, the shank
of terminal pin 22 at a point adjacent the free end particularly as
is indicated in FIG. 4. Connector block 28 is provided with a bore
adjacent the base end thereof, such as at 28A, with this bore being
arranged to accommodate ceramic sleeve member or insulator 28B
therewithin. The ceramic sleeve 28B has an internal bore as at 28C
to receive and accommodate output lead member 26, as indicated. A
metal sleeve member 28D is bonded hermetically about the outer
periphery of ceramic sleeve 28B, and may be brazed and thereby
sealed to the metallic enclosure 18, as illustrated. In order to
complete the assembly, a second sleeve element as at 28E is
provided adjacent the upper end of the sleeve so as to provide a
means for securing connector block 28 to ceramic sleeve 28B. Plug
seal 33 is provided for closing bore or opening 34 in the epoxy
member 17, with plug 33 being a resilient member having dimensions
selected so as to effectively seal opening 34.
With continued attention being directed to FIGS. 3 and 4, it will
be observed that cylindrical segment 20, which is bonded or
otherwise secured to the tubing element 35 of lead assembly 11 has
seals 23 and 24 arranged about the periphery thereof. Seal 23 is in
the form of a radially outwardly extending member having a
semi-circular cross-section, thereby presenting an outer
configuration similar to the outer portion of an "O"-ring. Seal 24
is significantly different from seal 23.
Seal 24 is provided with a resilient peripheral sleeve segment 40
which extends outwardly of the periphery of cylindrical segment 20,
and is provided with a raised resilient ring or sleeve member which
extends continuously about the outer periphery of cylindrical
segment 20. A raised resilient ring 41 extends continuously about
the outer periphery of sleeve 40, with the outer portion of ring 41
having a cross-section generally that of a semi-circle, and being
integrally molded generally diametrically to the outer surface of
peripheral sleeve 40. The outer diameter of members 23 and 41 are
generally approximately 0.20 mm greater than the inner diameter of
bore 19, thereby providing a substantial interference fit and
thereby accomplishing sealing. The utilization of the raised sleeve
40 provides axial support for ring 41, and thereby enhances or
preserves the sealing capability of ring 41 in spite of modest
axial misalignment and deflection between cylindrical segment 20
and the cylindrical segment receiving bore 19 formed in epoxy
member 17 of pulse generator 12. It will be observed that epoxy
member 17 is transparent, thereby enabling the visual determination
of the position of terminal pin 22 relative to connector block 28.
This is, of course, helpful during assembly of the pulse generator
to the lead assembly after placement of the lead assembly within
the patient.
In addition to the sealing surfaces provided by members 23 and 41,
it will be observed that the base end of cylindrical segment 20
seals against the tapered portion of bore 19. Therefore, three
serially arranged seals are provided, all of which contribute to
affecting a proper and effective seal for the lead assembly as it
enters the pulse generator.
As is apparent in FIG. 3, terminal pin 22 extends inwardly of
cylindrical segment 20, and terminates, where indicated, at a point
spaced from the center of seal 24 by a dimension "X". It is this
dimensional arrangement which accommodates radial deflection of the
pin 22 relative to the cylindrical segment 20, thereby facilitating
a seal when the set screw 31 is locked against the terminal pin
22.
Typically, in a lead assembly having a cylindrical segment 20 with
a diameter of 5.6 mm, the magnitude of dimension "X" is typically 2
mm. Workable dimensions would, of course, be somewhat broader, such
as in the range of from 1 to 5 mm.
The physical configuration of plug seal 33 is selected so as to
enhance the sealing achieved. Sealing surfaces are provided as at
45, 46, and 47. The outer diameter of plug seal 33 as at 47 is
greater than the inner diameter of bore 48, thereby effecting a
seal. Furthermore, in this connection, the dimension "X'"
illustrated in plug seal of FIG. 3 is less than the corresponding
dimension "Y" in the opening formed in the epoxy member 17 of pulse
generator 12. Therefore, by pre-selecting these dimensions as
described, a sealing surface is generated as at 45 and also 46
between the plug seal 33 and epoxy member 17.
In order to provide for the smooth transition between sealing
member or surface 41 and the inner surface of bore 19, the axial
spacing between terminal pin 22 and sealing surface 41 should be as
great as reasonably possible. Therefore, any misalignment or
canting between the lead assembly and the bore formed in the pulse
generator may be accommodated, with this accommodation being
obtained without sacrificing the quality of the seal formed between
the lead assembly and the pulse generator.
By way of actual procedure, after the electrode has been
satisfactorily placed in situ with proper electrical thresholds
determined, and the pocket for the pulse generator has been
prepared in the usual way, the leads are then arranged to be
connected to the pulse generator. Initially, the external surface
of cylindrical segment 20 is coated with a film of sterile mineral
oil. The proximal end of the lead assembly including the terminal
pin and cylindrical segment 20 are inserted into bore 19, with
insertion continuing until terminal pin 22 is visibly within and
properly sealed in connector block 28. Set screw 31 is then
tightened with an Allen wrench with insertion pressure continuing
to be applied between the proximal end of the lead assembly 11 and
pulse generator 12 such as the shank portion of terminal pin 22.
The continued application of insertion pressure assists in
effecting the seal, and the application of firm forces between set
screw 31 and terminal pin 22 provide a reliable electrical
connection between the surfaces of set screw 31 and terminal pin
22. The plug seal member 33 is then coated with medical adhesive,
if desired, or merely inserted into the opening 34 with the tip of
the Allen wrench, bore or opening 50 in plug 33 being formed to
receive an Allen wrench therewithin. A suture hole is illustrated
as at 51, and is provided for securing the pulse generator in the
pocket to prevent undesired migration of the assembly.
By way of materials of construction, enclosure 18 of pulse
generator 12 is preferably fabricated from stainless steel, with
epoxy cap member 17 being, of course, prepared from thermosetting
epoxy resins suited for implant purposes. Leads such as lead 11 are
formed of conductive elements such as elements 14 together with
silicone rubber tubular sleeves. Furthermore, conductor 15 is
formed with a hollow core therewithin in order to permit the lead
assembly to receive an internal stylet for use as a placement aid.
Additional details of the structure of typical electrode lead
assemblies are given in the David Charles Amundson U.S. Pat. No.
4,033,355, entitled "ELECTRODE LEAD ASSEMBLY FOR IMPLANTABLE
DEVICES" and assigned to the same assignee as the present
invention.
While the apparatus illustrated in the specific embodiment herein
is a unipolar device, it will be appreciated that the lead assembly
and sealing arrangement illustrated will be equally suited for
bipolar structures. Also, the specific mode of operation of the
pulse generator is not critical to the functionality of the lead
assembly, and hence the lead assembly illustrated may be utilized
in combination with any type of implantable pulse generator. A
typical example of circuitry for use in such a pulse generator is
illustrated in, the Jon A. Anderson, et al U.S. Pat. No. 4,041,953,
entitled "CARDIAC PACER CIRCUIT", and assigned to the same assignee
as the present invention.
* * * * *